The needs for exchanging information between an airplane and the ground are constantly increasing since they are associated in particular with updating components of information systems of the airplane, with conveying flight information from ground stations, with conveying airplane maintenance information for optimizing operating costs, and with services made available to passengers.
During various stages of the operation of an airplane, different communications means need to be used depending on the situation of the airplane (stationary on the ground, taxiing, taking off or landing, continental flight, oceanic flight, or polar flight). Airplanes are thus fitted with a plurality of radiofrequency communications systems capable of connecting to the communications infrastructure that is the most appropriate for each of the operating stages of the airplane. Depending on the types of information being conveyed and on their potential impact on the safety of airplane operation, those communications systems must also satisfy reliability specifications that are constraining to a greater or lesser extent.
The communications systems in use comprise infrastructures that are specific to aviation communications, such as the ARINC communication addressing and reporting system (AGARS) or the aeronautical telecommunication network (ATN) which rely on very high frequency (VHF), high frequency (HF), or satellite links. Those historical networks are nowadays associated with the use of infrastructures based on “open world” technologies such as WiFi, WiMax, GSM, GPRS, and UMTS for use when the airplane is on the ground, or Swift64 and SBB when the airplane is in flight.
Even though having multiple accessible infrastructures is advantageous in terms of availability and reducing the cost of communications, in order to optimize costs airplane operators seek to optimize not only the weight and volume of on-board equipment and the impact of antennas on the aerodynamic behavior of the airplane, but also the costs of communication between the airplane and the ground.
In this general context, and in order to handle the increase in worldwide air traffic, new communications infrastructures are being defined and standardized. These infrastructures are designed to take charge of the exchanges of data that are needed for providing air traffic control by the authorities (air traffic services or ATS). This work has thus led to selecting a radiofrequency telecommunications system that is based on the worldwide interoperability for microwave access (WiMax) standard to define a communications system in a frequency band around 5 gigahertz (GHz) that has been dedicated by the international telecommunications union (ITU) for aviation applications. Its installation and use will progressively become required for commercial airplanes for the purpose of conveying the information needed for allowing the air traffic control system to take the airplane in charge. That system is for use when the airplane is on the ground, and it is therefore not suitable for use in flight. That system is referred to as AeroWimax or indeed as the aeronautical mobile airport communication system (AeroMACS). Throughout the present application, those two terms are considered as being synonyms.